Now, I'm new to the whole Airsoft thing, and I'm not accustomed to not getting specific materials used in my weapon systems. In this case, all I know about the 1911 Mk1 is that it's made of a "metal alloy". This isn't very descriptive, and it's bugging the hell out of me.

Straight out, I'm assuming that the "alloy" is not stainless steel. Most of the 1911s on the market made of stainless steel weigh in the 40 oz ~ 42 oz level, which the PTP is most definitely not. This leaves me with assuming it is something similar to aluminum, although the aluminum framed 1911 I know of is a bit heavier then the PTP. Whatever the PTP is, I'm assuming it is lower in density then aluminum.

What exactly is the metal alloy used? Does anyone know?

And furthermore, what is stopping KWA from actually using a steel frame and steel rails on the slide? This would IMO simulate the weight of a steel 1911, which is much more common then the aluminum and scandium 1911s.

The weights are "pretty close." I may be one of the few who trains with a Government Model -- I know I'm a subject of curiosity during training courses! -- but carry a Commander size.

My Mark I PTP weight 35.5oz loaded about 5oz less than my loaded (7+1) stainless Ed Brown Kobra Carry (Commander) and 10oz less than my Colt Government model. But she's 3.5oz heavier than my loaded Colt Commander with the aluminum frame. I'm still saving for an aluminum alloy Kobra Carry.

The weight in the Mark 1 is concentrated in the frame and magazine, the slide is very light weight.

Propelling the slide with the recoil forces of a 230g (15gm) .45ACP bullet moving 900fps is quite different from Green Gas pushing a 0.25gr pellet at 300fps. In round numbers the bullet is 60 times heaver than the pellet and is propelled to 3 times the velocity. A slide the mass of a M1911 in not required in an airsoft and to make it work would probably require a much larger amount of gas.

Of course I understand why the Slide has to be as light as it is, I just want the rails on the slide and the frame to be made of some serious materials since these areas are high stress zones.

A side note: The thumb safety's retention is almost non-existent, making me have to ride the safety when firing. I am not a fan of this at all, as my S&W doesn't do this. I suppose I have to take a dremel to that to fix this problem, but at this price point, I think this shouldn't be an issue.

Riding the safety is a requirement of the M1911. At least as it's taught at major schools like Gunsite. Your thumb should always be there if the pistol is in hand. Simply depress to take off-safe and hold it down when shooting.

I'm definitely not a big fan of riding the thumb safety. It's something I never have to do with any other pistol platform, and I don't do it with the 1911 platform either.

I love the 1911 platform since it points so naturally and has a light recoil, but riding the safety kills the ergos for me. I'm at the verge of just gluing the darn thing down as I don't want to deal with it.

I figure it's an alloy featuring aluminum as it's main constituent. Taking the grips off revealed the weights used to simulate the real 1911, so it can be nothing but aluminum given the price point. I can already see parts of the frame showing bits of wear and tear, which makes me doubt the longevity of the gun. Oh well, I suppose it didn't cost all that much, so that's what I can expect out of it.

Don't doubt the longevity of the gun. As long as you take care of it and not throw it against a brick wall, the gun will last a long, long time. I've even dropped my M9 PTP twice on concrete... hasn't been broken yet!!

Dropping a gun on concrete would count as abuse, and if one survived two of those, I'd say that's a pretty good testament to the system's durability. I expect that out of my real firearms, but having airsoft guns able to survive that seems pretty nice to me. Still... can't really get over my prejudice against aluminum D:

I understand your unwillingness to accept aluminum. Think of it this way, how Chuck put it: green gas is only so strong to move solid objects. You need to make sure the slide and materials used to construct these guns that blowback using a controlled gas expansion effect are light enough... if you make them heavier, then the guns will turn into non-blowback guns, and those aren't fun, now are they?

Yeah, I understand light weight materials are unavoidable on the slide. I'll just never be a fan of low grade aluminum as the basis material. 7075 would be preferable, though I would really like to see some Scandium see use as well. I'm sure the price would go up a bit as well, but I for one am willing to pay for it if it means the gun will last decades rather then years.